Differential termination and attenuator network for a measurement probe having an automated common mode termination voltage generator

摘要

A differential termination and attenuator network having an automated common mode termination voltage generator includes first and second termination resistors coupled in parallel with corresponding resistive attenuator circuits. A monitoring circuit coupled to input nodes of the network generates an output signal representative of the combination of a DC common mode voltage on the input nodes and an adjustable termination voltage. A control circuit generates scaled termination and compensation voltages and associated drive currents using the adjustable termination voltage and the monitoring circuit output signal. The scaled termination voltage and the scaled compensation voltage operate on the differential termination and attenuation network to optimize the dynamic range of a differential amplifier connected to the first and second attenuator outputs. An automated termination voltage generator automatically adjusts the adjustable termination voltage to match the DC common mode input voltage, which nulls the DC currents at the input nodes.